Transatrial patient temperature control catheter

ABSTRACT

A transatrial intravascular temperature management catheter has a lower heat exchange segment positionable in the inferior vena cava and an upper heat exchange segment positionable in the superior vane cava, with a connecting segment lying between the two and positionable in the right atrium. A temperature sensor on the distal tip of the upper heat exchange segment provides accurate core body temperature signals for feedback purposes since the blood flowing past the sensor has not yet reached the heat exchange segment.

FIELD OF THE INVENTION

The present application relates generally to patient temperature controlsystems.

BACKGROUND OF THE INVENTION

It has been discovered that the medical outcome for a patient sufferingfrom severe brain trauma or from ischemia caused by stroke or heartattack or cardiac arrest is improved if the patient is cooled belownormal body temperature (37° C.). Furthermore, it is also accepted thatfor such patients, it is important to prevent hyperthermia (fever) evenif it is decided not to induce hypothermia. Moreover, in certainapplications such as post-CABG surgery, it might be desirable to rewarma hypothermic patient.

As recognized by the present application, the above-mentioned advantagesin regulating temperature can be realized by cooling or heating thepatient's entire body using a closed loop heat exchange catheter placedin the patient's venous system and circulating a working fluid such assaline through the catheter, heating or cooling the working fluid asappropriate in an external heat exchanger that is connected to thecatheter. The following U.S. patents, all of which are incorporatedherein by reference, disclose various intra vascularcatheters/systems/methods for such purposes: U.S. Pat. Nos. 6,881,551and 6,585,692 (tri-lobe catheter), U.S. Pat. Nos. 6,551,349 and6,554,797 (metal catheter with bellows), U.S. Pat. Nos. 6,749,625 and6,796,995 (catheters with non-straight, non-helical heat exchangeelements), U.S. Pat. Nos. 6,126,684, 6,299,599, 6,368,304, and 6,338,727(catheters with multiple heat exchange balloons), U.S. Pat. Nos.6,146,411, 6,019,783, 6,581,403, 7,287,398, and 5,837,003 (heat exchangesystems for catheter), U.S. Pat. No. 7,857,781 (various heat exchangecatheters).

Present principles understand that accurately and constantly measuringpatient core temperature for feedback purposes and maximizing the rateof cooling for therapeutic purposes are among the challenges posed byintravascular temperature control. Accurate patient core temperaturemeasurements can be provided by rectal probes, esophageal probes,bladder probes, and the like but such probes are uncomfortable for awakepatients. Placing a sensor on the catheter itself in a vein of thepatient avoids the need for an uncomfortable separate probe but sincethe catheter changes the temperature of the blood flowing past thecatheter, to avoid the “thermal shadow” of the hot or cold catheter,cooling or heating of the patient periodically must be temporarilysuspended long enough for the temperature of the blood near the sensorto stabilize at actual core body temperature. This undesirably prolongscooling, for instance, when it is desired to cool the patient.

As to maximizing the rate of cooling, the larger the heat transfer areaof the catheter, the faster it can cool but size limits, are reachedeven when using the entire inferior vena cava as a placement site.Existing catheters must accommodate the vein into which they are placed.With the above recognitions in mind, present principles are provided.

SUMMARY OF THE INVENTION

Accordingly, a transatrial intravascular temperature management catheterincludes a lower heat exchange segment positionable in the inferior venacava of a patient without blocking the inferior vena cava such thatblood can flow past the lower heat exchange segment. The catheter alsoincludes an upper heat exchange segment positionable in the superiorvane cava of the patient without blocking the superior vena cava suchthat blood can flow past the upper heat exchange segment. Furthermore,the catheter includes a connecting segment connecting the heat exchangesegments and positionable in the right atrium of the patient. Workingfluid can be circulated through the heat exchange segments and theconnecting segment to and from a heat exchange system external to thepatient. The heat exchange system establishes a temperature of theworking fluid at least in part based on a signal representing patienttemperature. A temperature sensor on the distal tip of the upper heatexchange segment provides the signal representing patient temperature.

In some implementations, a heat exchange segment can be established byan elongated generally cylindrical balloon, or by a series ofnon-straight, non-helical links through which the working fluid flowsserially from link to link. Or, a heat exchange segment can beestablished by a straight central supply tube surrounded by threehelical return tubes. Yet again, a heat exchange segment can beestablished by alternating segments of bellows regions arid helicallyfluted regions. If desired, the upper heat exchange segment may besmaller than the lower heat exchange segment to diameter and/or length.The connecting segment may be an elongated tube having a cylindricalouter surface throughout its length, and the connecting segmenttypically has a smaller diameter than either of the heat exchangesegments.

In another aspect, a catheter includes a lower heat exchange segmentpositionable in the inferior vena cava of a patient without blocking theinferior vena cava such that blood can flow past the lower heat exchangesegment. A connecting segment is connected to and extends away from thelower heat exchange segment and is positionable in the superior venacava through the right atrium of the patient. The connecting segmentresides in the superior vena cava when the lower heat exchange elementis disposed in the inferior vena cava. Working fluid can be circulatedthrough the heat exchange segment to and from a heat exchange systemexternal to the patient. The heat exchange system establishes atemperature of the working fluid at least in part based on a signalrepresenting patient temperature. A temperature sensor on the connectingsegment provides the signal representing patient temperature.

In another aspect, a method includes advancing a catheter into apatient's inferior vena cava from a femoral insertion point, through theright atrium of the patient, and into the superior vena cava of thepatient such that a heat exchange part of the catheter remains in theinferior vena catheter and a temperature sensing part of the cathetersimultaneously resides hi the superior vena cava. Working fluid iscirculated through the heat exchange part to exchange heat with bloodflowing past the heat exchange part in the inferior vena cava. Thetemperature of the working fluid is controlled responsive to signalsfrom the temperature part. Alternatively, the catheter may be advancedinto the patient from the opposite direction, i.e., from a neckinsertion point such as the jugular vein or subclavian vein, through thesuperior vena cava, right atrium, and the inferior vena cava to end at aplacement in which respective heat exchange parts are in the inferiorand superior vena cavae and a connecting part between the heat exchangeparts is in the right atrium.

The details of the present invention, both as to its structure andoperation, can best be understood in reference to the accompanyingdrawings, in which like reference numerals refer to like parts, and inwhich:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram showing the transaxial catheter advancedinto both vena cavae with the connector portion of the catheter disposedin the right atrium;

FIG. 2 is a perspective view of a first example catheter with a firstexample heat exchange member with plural non-straight, non-helicallinks, with portions of the heat exchange member broken away;

FIG. 3 is a perspective view of a second example catheter with secondexample heat exchange members configured as hollow balloons;

FIG. 4 is a side view of a third example catheter with a third exampleheat exchange member formed from a straight central supply tubesurrounded by three helical return tubes;

FIG. 5 is a perspective view of a fourth example catheter with fourthexample heat exchange members that consist of alternating segments,along a metal tube, of bellows regions and fluted regions, with portionsof the catheter broken away; and

FIG. 6 is a cut-away view of the catheter shown in FIG. 5.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring initially to FIG. 1, a transatrial intravascular temperaturemanagement catheter 10 is in fluid communication with a cathetertemperature control system 12 that includes a processor executing logicdescribed in one or more of the patents referenced herein to control thetemperature of working fluid circulating through the catheter 10 inaccordance with a treatment paradigm responsive to patient coretemperature feedback signals. In accordance with present principles, thecatheter 10 can be used to induce therapeutic hypothermia in a patient14 using the catheter, in which coolant such as but not limited tosaline circulates is a closed loop, such that no coolant enters thebody. Such treatment may be indicated for stroke, cardiac arrest(post-resuscitation), acute myocardial infarction, spinal injury, andtraumatic brain injury. The catheter 10 can also be used to warm apatient, e.g., after bypass surgery or burn treatment, and to combathyperthermia in, e.g., patient suffering from sub-arachnoid hemorrhageor intracerebral hemorrhage.

As shown, working fluid may be circulated between the heat exchangesystem 12 and catheter 10 through supply and return lines 16, 18 thatconnect to the proximal end of the catheter 10 as shown. Note that asused herein, “proximal” and “distal” in reference to the catheter arerelative to the system 12. A temperature signal from the below-describedcatheter-borne temperature sensor may be provided to the system 12through an electrical line 20 or wirelessly if desired. The catheter 10,in addition to interior supply and return lumens through which theworking fluid is circulated, may also have one or more infusion lumensconnectable to an IV component 22 such as a syringe or IV bag forinfusing medicaments into the patient, or an instrument such as anoxygen or pressure monitor for monitoring patient parameters, etc.

The catheter 10 includes a lower heat exchange segment 24 that ispositionable through a femoral insertion point into the inferior venacava 26 of the patient 14 without blocking the inferior versa cava 26such that blood can flow past the lower heat exchange segment 24 asshown. Also, in some implementations the catheter 10 may include anupper heat exchange segment 28 that is positionable in the superior vanecava 30 of the patient without blocking the superior vena cava 30 suchthat blood can flow past the upper heat exchange segment 28. The upperheat exchange segment 28 can be smaller than the lower heat exchangesegment 24 by virtue of having a smaller diameter than the lower heatexchange segment and/or by being shorter than the lower heat exchangesegment. In any case, the upper heat exchange segment 28 is advancedfirst through the femoral insertion point, through the inferior venacava and right ventricle, and into the superior vena cava, with thelower heat exchange segment 24 following and being disposed in theinferior vena cava once the upper heat exchange element 28 resides inthe superior vena cava. Advancement may be over a guidewire or guidecatheter and may be effected using fluoroscopy.

A connecting segment 32 connects the heat exchange segments 24, 28 andis positionable in the right atrium of the heart 34 of the patient.Working fluid is circulated through the heat exchange segments 24, 28and the connecting segment 32 to and from the heat exchange system 12external to the patient. Preferably, neither heat exchange segment 24,28 extends into the atrium of the heart 34; only the connecting segment32 is disposed in the heart. This is because the connecting segment,which can be a simple elongated thin cylindrical tube with only a supplyand return lumen for the upper heat exchange segment 28 (and in someembodiments with one or more infusion lumens if desired), is smaller indiameter than the heat exchange segments 24, 28 so as to minimize therisk of contacting the heart muscle. Note that in some embodiments theupper heat exchange segment 28 may be omitted and the connecting segment32 may be a very thin tube or even a wire that extends through the rightatrium into the superior vena cava 30 for the sole purpose of bearingthe below-described temperature sensor.

Indeed and with greater specificity, a temperature sensor 36 may bemounted on the distal tip of the upper heat exchange segment 28 toprovide a signal representing patient temperature. Without limitation,the sensor 36 may be a thermistor, thermocouple, resistance temperaturedetector (RTD), or other suitable sensor. In any case, it will beappreciated that since blood in the superior vena cava flows toward theheart, the blood reaches the sensor 36 before it can be heated or cooledby the upper heat exchange-segment 28. In other words, owing to theplacement of the catheter 10 through the heart 34 with the sensor 36 inthe superior vena cava, the sensor 36 is upstream of the “thermalshadow” of the heat exchange segment 28 and so provides an accurateindication of core body temperature.

FIGS. 2-6 show example non-limiting embodiments of the lower heatexchange segment 24, it being understood that the same shapes may beused for the upper heat exchange segment 28. In FIG. 2 a catheter 100has a heat exchange segment 102 established by a series of non-straight,non-helical links 104 through which the working fluid flows seriallyfrom link to link. Further details of the construction and operation ofthe catheter 100 are set forth in the above-referenced U.S. Pat. No.6,796,995.

FIG. 3 shows a catheter 200 that has one or more axially-spacedcylindrical balloons 202 that carry circulating working fluid to andfrom a heat exchange system 204. The catheter 200 shown in FIG. 3includes two additional infusion lumens connected to respective infusiontubes 206, with the various external tubes joining respective internalcatheter lumens at a hub 208 which may be formed with suture wings 210for suturing the hub 208 to the skin of the patient. The infusion lumensmay terminate at respective axially-spaced infusion ports 212. Furtherdetails of the construction and operation of the catheter 100 are setforth in the above-referenced U.S. Pat. No. 6,368,304.

Yet again, FIG. 4 shows a catheter 300 that has a straight centralsupply tube 302 surrounded by three helical return tubes 304. Furtherdetails of the construction and operation of the catheter 300 are setforth in the above-referenced U.S. Pat. Nos. 6,881,551 and 6,585,692.

FIGS. 5 and 6 show a catheter 400 that may be made of a metal such asgold and that has alternating segments of bellows regions 402 andhelically fluted regions 404. Further details of the construction andoperation of the catheter 400 are set forth in the above-referenced U.S.Pat. Nos. 6,551,349 and 6,554,797.

While the particular TRANSATRIAL PATIENT TEMPERATURE CONTROL CATHETER isherein shown and described in detail, it is to be understood that thesubject matter which is encompassed by the present invention is limitedonly by the claims.

What is claimed is:
 1. A catheter, comprising: a first heat exchangesegment configured to be positioned in the inferior vena cava of apatient without blocking the inferior vena cava such that blood can flowpast the first heat exchange segment; a second heat exchange segmentconfigured to be positioned in the superior vane cava of the patientwithout blocking the superior vena cava such that blood can flow pastthe second heat exchange segment when the first heat exchange segment islocated in the inferior vena cava; and a connecting segment connectingthe heat exchange segments and configured to be positioned in the heartof the patient when the first heat exchange segment is in the inferiorvena cava and the second heat exchange segment is in the superior venacava, the heat exchange segments and the connecting segment configuredsuch that working fluid circulates to and from a heat exchange systemexternal to the patient and through the heat exchange segments and theconnecting segment.
 2. The catheter of claim 1, wherein the connectingsegment includes an elongated thin cylindrical tube with a supply and areturn lumen for the second heat exchange segment.
 3. The catheter ofclaim 1, wherein the connecting segment has a smaller diameter than atleast the first heat exchange segment.
 4. The catheter of claim 1,comprising a temperature sensor on a distal segment of the second heatexchange segment.
 5. The catheter of claim 1, wherein the second heatexchange segment is smaller than the first heat exchange segment.
 6. Thecatheter of claim 1, wherein the connecting segment has a smallerdiameter than both the first and second heat exchange segments.
 7. Thecatheter of claim 1, wherein the second heat exchange segment has asmaller diameter than the first heat exchange segment.
 8. The catheterof claim 1, wherein the second heat exchange segment is shorter than thefirst heat exchange segment.
 9. A catheter, comprising: a first heatexchange segment; a second heat exchange segment; a connecting segmentconnecting a first end of the first heat exchange segment with a firstend of the second heat exchange segment and being smaller in diameterthan the first and second heat exchange segments, working fluid beingcirculatable through the first and second heat exchange segment to andfrom a heat exchange system external to the patient, the heat exchangesystem establishing a temperature of the working fluid at least in partbased on a signal, the connecting segment including a tube with a supplyand a return lumen; and a temperature sensor on the catheter providingthe signal.
 10. The catheter of claim 9, wherein the first heat exchangesegment is configured to be positioned in the inferior vena cava of apatient without blocking the inferior vena cava such that blood can flowpast the first heat exchange segment while the second heat exchangesegment is positioned in the superior vena cava through the heart of thepatient.
 11. The catheter of claim 9, wherein at least one heat exchangesegment is established by an elongated generally cylindrical balloon.12. The catheter of claim 9, wherein at least one heat exchange segmentis established by a series of non-straight, non-helical links throughwhich the working fluid flows serially from link to link.
 13. Thecatheter of claim 9, wherein at least one heat exchange segment isestablished by a straight central supply tube surrounded by threehelical return tubes.
 14. The catheter of claim 9, wherein at least oneheat exchange segment is established by alternating segments of bellowsregions and fluted regions.
 15. The catheter of claim 14, wherein thefluted regions have helical flutes.
 16. Method comprising: providing acatheter advanceable into a patient's inferior vena cava from a femoralinsertion point, through the right atrium of the patient, and into thesuperior vena cava of the patient such that a heat exchange part of thecatheter remains in the inferior vena cava and at least a temperaturesensing part of the catheter can simultaneously reside in the superiorvena cava; providing a pump for circulating working fluid through theheat exchange part to exchange heat with blood flowing past the heatexchange part in the inferior vena cava; and providing a controller forcontrolling temperature of the working fluid responsive to signals fromthe temperature part.
 17. The method of claim 16, wherein the heatexchange part positionable in the inferior vena cava is a first heatexchange part and the temperature sensing part also includes a secondheat exchange part distanced from the first heat exchange part andfluidly connected thereto.
 18. The method of claim 16, wherein thecontroller is configured for controlling the temperature of the workingfluid to first core body temperature of the patient.
 19. The method ofclaim 16, wherein the controller is configured for controlling thetemperature of the working fluid to raise core body temperature of thepatient.